As one of methods of recording an image, a letter, a pattern, and the like (hereinafter, these are collectively referred to as image) on a recording medium using ink, there is an ink-jet system. Heretofore, as the ink used in an ink-jet system (hereinafter, referred to as ink for ink-jet), many aqueous inks that form an image on a substrate having the ink absorbability, such as paper and cloth, have been proposed. Meanwhile, in recent years, an aqueous ink that can also form an image on a substrate having no ink absorbability (hereinafter, referred to as non-absorbing substrate) such as resin film, plastic, and metal, or a substrate having the low ink absorbability (hereinafter, referred to as low-absorbing substrate) has been proposed. In addition, an image is formed by volatilization of a solvent such as water and an organic solvent contained in the aqueous ink, on the surface of a recording medium.
Since on the surface of a non-absorbing substrate or a low-absorbing substrate, the conventional aqueous ink does not permeate the substrate, and is deposited on the surface of the substrate, a drying speed is slow. For that reason, when the aqueous ink is discharged on the surface of the non-absorbing substrate or the low-absorbing substrate, if the time until the aqueous inks are brought into contact with each other on the substrate surface is short, there is a possibility that the aqueous inks are brought into contact with each other while the aqueous inks are not sufficiently dried. Hence, on an image that is formed on the surface of the non-absorbing substrate or the low-absorbing substrate, beading (phenomenon that adjacent dots are connected, and irregular gaps and concentration unevenness are generated), and inter-color bleeding are easily generated.
Then, printing systems using an aqueous ink and a reaction liquid (color-fixing agent) have been variously provided, as constituent features that can suppress generation of beading and inter-color bleeding, regardless of an interval between discharges of the aqueous ink, in an image that is formed on the surface of the non-absorbing substrate or the low-absorbing substrate. For example, Patent Document 1 discloses a printing system using an aqueous ink containing an anionic pigment dispersant, a latex (emulsion), a surfactant, a co-solvent, a coloring agent, water, and the like, and a color-fixing agent containing a cationic polymer, a surfactant, water, and the like.